The present invention generally relates to devices capable of delivering precisely metered fluid volumes. Specifically, the invention includes a pump that may provide both a microdose and macrodose so as to accurately deliver a precise volume of fluid with high resolution adjustment over a wide range of microdose and macrodose volumes. The invention can be configured for use in fields which include medical, pharmaceutical, food and beverage, industrial process, laboratory, and chemical, as well as commercial and consumer applications.
Precise dosing pump systems are complex and expensive systems, are highly specialized, and are limited to particular applications. The highly specialized nature of dosing pumps systems limits their performance capabilities to a narrow range of operation. Furthermore, due to their high cost, dosing pump systems are typically limited to high-end applications in fields such as medical and industrial, while commercial and consumer applications have limited access to the technology.
Generally, dosing pumps are electrically powered devices, and may be operated utilizing several technologies such as solenoids, gears, a diaphragm and peristaltic actuation. Regardless of the pump technology, however, dosing pumps are typically designed for and limited to providing very low flow rates such as 0.01 millileters per minute to 5 milliliters per minute. In these prior systems, the low flow rate is necessary in order to precisely control the output of the fluid. The drawback to the low
flow rate, however, is that dosing pump systems have a limited range of adjustability such that they are not effective to operate outside of the nominal design flow rate. Use of a higher flow rate dosing pump, such as a pump that operates in a range of 20 milliliters per minute to 50 milliliters per minute, in order to expand the range of flow rates is typically not an option because the increased flow rate comes at the loss of accuracy and precision. Therefore, dosing pumps capable of precisely controlling macrodose flow are expensive and highly uncommon.
Both precise microdose pumps as well as macrodose pumps tend to be expensive. Also increasing the cost is the need of certain applications that require both microdosing and macrodosing because more than one pump is required to achieve all of the desired dosing ranges. Current dosing pumps lack the necessary degree of adjustability to cover large ranges of flow rate.
Further drawbacks of prior dosing pump systems are the variety of devices in addition to the pump that are required in order to monitor and control the flow of fluid. Flow meters, adjustable flow controls, pressure sensors, and temperature sensors are all needed in order for dosing pump systems to achieve their precision and monitor flow. These additional components contribute to the complexity and cost of the system, as well as add physical bulk.
The sensitivity of readily available flow sensors, such as turbine sensors, is also not sufficient for accurately determining the flow rate of fluids at microdosing levels, generally within the range of 0.01 millileters per minute to 5 milliliters per minute. In the case of traditional turbine sensor, the microdose flow rate cannot adequately spin the turbine to generate sufficient signal to determine the actual flow rate of the fluid. Thus, In a traditional microdosing system, such flow sensors cannot be utilized because the pump operates to draw in and expel fluid at essentially the same microdosing rate resulting in an input flow and an output flow that are each at microdosing levels. In such systems, a specialized microdosing sensor must be utilized. Microdosing sensors have significant drawbacks such as a high cost, generally thousands of dollars. Additionally, they are often application specific and must be specially designed.
The selection of these components is typically based on achieving a nominal microdose or macrodose flow rate fluid to enable a specific dosing pump to expel fluids of a particular, narrow viscosity range. The design of the particular dosing system is thus limited to a particular flow rate for a particular fluid viscosity. If a change to the nominal flow rate is desired, or the viscosity of the fluid changes, the dosing pump must be re-engineered, or replaced altogether, along other components of the dosing pump system (flow controls, etc.) in order to maintain the precision of the system.
In summary, existing dosing pump systems can be configured to provide accurate, high-precision fluid delivery. However, this is achievable only within a narrow operational range and through the assembly of a complex and expensive flow control system.